Drilling apparatus



Dec. 18, 1934. M. P. HOLMES DRILLING APPARATUS Filed Nov. 16, 1923 3 Sheets-Sheet l .YANN

Dec. 18, 1934. M, P. HOLMES DRILLINQ APPARATUS Filed Nov. 1e, 1923 5 sheets-sheet 2 MSN Dec. 18, 1934. M. p HOLMES 1,984,373

DRILLING APPARATUS Filed Nov. 16, 1923 5 Sheets-Sheet 3 @Ill/11114 IM l Q '2% '3 N any.

Patented Dec. 18, 1.934

Irmrjusn l f y n kMorris I. lF/Iolmes, Claremont, N, Lil., assignorl Sullivan Machinery Companyga corporation nl!` Massachusetts This "inventionfrelates kto'drillingapparatus and more `particularlyto'a drilling apparatus of the self-propelledv type `especially adapted to use vention is to provide Another object of this inan improved drilling apparatus lhaving 'improved tooladjusting, supporting, and driving means, whereby the tool may bek quickly adjusted relativeto. th'evworking face and "fed relative to the workin an improved manner. proved drilling appara motor is utilized in along 'the "trackway, a ingjr'neans, and lfor `dr one or incre tools. Sti

propelling the 'apparatus d justing ythe. tool supportiving the tool rotating 'andy feeding means, and `Whiohlends-itself to use with.

llanother object is to provide anv improved drilling apparatus of 'the `ntlultiple tool type wherein Aimproved and simplified' power operated mechanism is employed for'independently adjusting the tool supports "whereby the tools may lbe independently positioned relaanother object 'isto pro-1 V tive to the work. Yet

' vide 'an improved tru ck mounted self-propelled drilling apparatus of the multipletooltype which may gbe vquicklyv transported from place 'to place and vset up with facility, thereby materially decrea-sing the time consumeduwith'the resultant decrease in labor cost.

vide an improved coal drillingapparatu'sfof the,

Another 4object isjto `promultiple tool type having improved 'adjustable supporting means for bottoni and the ribs other objects of this invention will, however,sub.`

sequently more fully l proceeds;

In`the accompanying drawings therer is shownfor purposes of illustration one forrn which the.

invention may assume lnthese drawings, y l l Fig. -l is a plan View of vthe improved drilling apparatus, the `drilling tools being'shown adjust-f appear as the description;

in practice.

ed into a plurality `of lateral positions. l .u Fig. 2 is'a `side elevational View of the drilling app'aratusfshown in Fig. 1, the drilling tools being shown in a plur positions.l

ality of vertically .adjustedl Fig. 3 is "a cetrai longitudinal vertical sectional view through one of the'drilling tools, per se, t'he @View being taken :substantially Aon line 3&3 of"Fig. 1.` l A fl'ig.l L is 'a transverse liorigzontalsectional view 5 takenfsubstantimly on linee-54er Fig. 2.

Fig. 5 is a vertical section-ai view takenlsubstantially von line `5-j"l5 o'ffFg. l. l l

jFig; 6 latransvers'e verticalsectional view taken substantially on line 6-'6 of Fig. 5.

Fig. 7 is ja-deta'ilview illustrating the operating n'ieaiis for l'the lreverse 'clutch' mechanism. Fig. 8 isla detail sectionallview illustratingfo'ne ofujth'e locking "devices 'for the .tool supporting tur'ritableslH l f 1 `)llllfhile"the features [of -lmyinvention are 'in ,the nain equallyapplicable to a"singlej"irl1 mechanis'rrnfiny the,illustrativeembodimentl of the invention there `is shown a drilling "apparatus 'of the'v y lWheel fr noiirited; f. l"self-propelled, lmultiple spindle lormultiple Ltool type generally comprisin'g, a fwhee'led `truck r1 on which areisupported drilling tools `2 and. 3, by "means 'of improved `acl-.- justab'le supporting 'ineans generally' 'designated 4 foreach tool; Asshowrn the.`wheeled Itruc'zk l1 comprises a truck 'frarn'e or `body 45 mounted on wheels '6 adapted"l toy run Ikalong a traokwatr '7.

Thewheelsj are hereinj'secured .to ffronty 'and rear axles 8 vand 9 xjou'rrraled. in suitable axle boxesfcarried by Athe truck body. L Rigidly r'noun'ted uponthe truckbody atitsforward'end isa frarrrefor housing loin which certaint'ransmissionjkelernents of gthe truck'wheel driving and tool 'adjustingfdriving ndffeeding means are housed, aswill later be described. Supported on 3 tliisfrainejorhousing I() is a vertical motor 11, herein preferably of 'thereversibleelectric type, having iixed to `the lower endy of its armature shaft, 12 a 'motorjpinion 13 projecting vdownwardlyiwitliin the housing 10; VMeshing with this 'motor pinion isa spur gear '14 keyed at 15 to a vertical shaft 1'6 suitably journaled within thejframe '1o. A p y i The'dmpro'ved truck wheel 'driving 'mechanism herein comprises abevel pinion 17 herein formed integran witntheiiower end df the shaftis and meshing with, Oppositely rotating reverse ybevels ljand 19. fThesebeveljgearslB and 19, as shown inFiggare journaled on a transversek horizont'al "shaft 20, infturnjournaledwithin lthe housing*1o. l 'Keye'djto the opposite ends of this shaft 2l) at opposite 'side'sof thertruck body are chain spro'cketsQl tand. 22 respectively, the sprocket ,21 being connected by a 'chain 'and fsprocket conne'ctlon2ftoftlierear axle 9, while 4the sprocket` 22 is connected to the front axle 8 by a chain and sprocket connection 24. As shown in Fig. 6 the bevel gear 18 carries a series of friction plates 25 interleaved with similar friction plates 26 carried by a clutch member 27 keyed at 28 to the shaft 20. Similar friction plates 29 and 30 are carried respectively by the bevel gear 19 and a clutch member 31 also keyed to the shaft 20. The friction clutches within the bevel gears 18 and 19 are adapted to be alternatively applied to connect one or the other of the bevel gears, to the shaft to thereby effect drive of the latter in opposite directions by means of a clutch applying member 32 slidably mounted for endwise movement on the adjacent hubs of the bevel gears 18 and 19. Engaging this clutch applying member is a shipper member 33 fixed to a transverse operating rod 34 slidably mountedwithinthe frame 10. This clutch operating rod is adapted to be shifted axially by a suitable operating lever 35 pivotally mounted on the frame 10 at one side of the truck (see Fig. 1). i

The mechanism for driving the tool rotating and feeding mechanism herein comprises spur gears 36 and 37 hav-ingv their axes lying in the same vertical transverse-plane and spaced equally from the longitudinal center of the apparatus. The gear 36 herein drives the feeding and rotating means ofthe drilling tool 2 while the gear 37 drives the rotating and feeding means of the drilling tool 3. As the driving connections between the gears 36 and 37 and the rotating and feeding means of the drilling tools 2 and 3 are identical, it is thought that a description of the driving connections for 'one will suffice for both. As shown in Fig. the spur gear 36 is keyed at 38 to the lower end of `a vertical shaft 40 journaled in suitable bearings carried by a swivel frame or housing 41. It will herein be noted that the swivel frame 41 has secured thereto by means of screws .42 an'annular bearing member 43 rotatably mounted within bearing sleeves 44. These bearing sleeves 44 are supported by the frame and are held in position by an annular retaining ring 45 bolted to the frame 10. It will therefore be evident that the swivelv frame, together with its bearing structure, forms a hori- Zontal turntable mounted on the frame-10 for rotation about a vertical axis and supporting the drilling tool 2. Again referring to the tool rotating and feeding mechanism, it will be observed that the vertical shaft 40 has keyed thereto at its upper end a bevel pinion 46 meshing with a bevel gear 47 (see also Fig. 4) journaled on a transverse horizontal stud 48.` As 'shownthe stud 48 is keyed at 49 to the hub portion of a swingable housing or frame 50 mounted for rocking movement about a transverse horizontal axis within roller bearings 51 supported within the opposite sides of the swivel frame 41. The tiltable frame 50`has a cylindrical external bearing surface 52 which engages the inner periphery 53 of the swivel housing and these surfaces cooperate to form an additional bearing for the frame 50 during'its rocking movement. 'I'he forward portion of the swivel frame 41Vis cut away at'54 and a portion of the frame 55 of the frame 50 projects laterally through the opening formed by this cut away portion. Again referring to Fig. 5 it will be noted that the bevel gear 47 meshes with reverse bevels 56 and. 57. The bevelfgears 56 and 57 are keyed toclutch housings 58 and 58a respectively. The clutch housing 58 carries a series of friction plates 59 interleaved with a series .of similar plates GOcarried by ashaft 61.

The shaft 61 is journaled at its opposite ends within suitable ball bearings carried by the swingable housing 50. Similar friction plates 62, 63 are carried by the clutch housing 584 and the shaft 6l respectively. The operating mechanism for alternatively applying the clutches within the clutch housings 58 and 58a to thereby connect one or the other of the reverse bevels 56, 57 to the shaft 61 herein comprises a Vclutch applying member 64 surrounding and axially movable relative to the shaft 61. Engaging this clutch applying member 64 is a clutch shipper member 65 (see Fig. 7) pivotally mounted at one end as at 66 within slotted bearings formed on the inner end of the stud 48 (see also Fig. 4). As illustrated, the shippermember 65 is at its other end vertically slotted at 67 and engaging this slot is an `eccentric member or crank pin 68 carried on a shaft 69 rotatably mounted within and extending axially through one of the hub portions of the swinging frame 50. Rotatably mounted on the outer end of this shaft 69 is a lever 70 for yieldingly loading the clutches and having suitable spring pressed locking means 71 for maintaining the lever in its different adjusted positions. It will thus be seen that when the lever 70 is swung in one direction or the other the eccentric pin 68 moves Within the slot 67 and as a result the shipper member 65 is swung about its pivot thereby moving the clutch applying member 64 axially in one direction or the other to connect one or the other of the reverse bevels 56, 57 to the shaft 61. It will thus be evident that the shaft 61 may be driven in one direction or the other at will, the clutches being yieldably loaded in each case.

. As shown in Figs. 4 and 5, the shaft 61 has keyed thereto at 72 a spur pinion 73 which drives the adjusting mechanism for the drill supporting means 4 as will later be described. Alined with the shaft 61 and also keyed to the pinion 73 is a main transmission shaft 74. This transmission shaft 74 is arranged concentrically within and extends through a forwardly projecting tubular supporting arm or boom 75 mounted for rotation about its longitudinal axis within bearing sleeves 76 carried respectively by a frame 77 bolted to the laterally projecting portion 55 of the swinging frame 50, and a frame 78 fixed to the outer end of the frame 77. As shown in Fig. 3 the tubular supporting arm or boom 75 has secured thereto by screws 79 at its outer end a swivel frame or bearing bracket 80. The drilling tools are swiveled on the bearing brackets 80 as will later be described. In this instance the outer end of the main drive shaft 74 has keyed thereto a bevel pinion 81 meshing with a larger bevel ring gear 82. The bevel ring gear 82 is rotatable about an axis perpendicular to the axis of the drive shaft 74 and is journaled on a ball bearing 83 suitably supported by a bearing bracket 84 and a swivel plate 85. This swivel plate 85 is rigidly secured by screws 86 to the bearing bracket 84 and is herein rotatably mounted in a bore 87 arranged concentrically with the bevel gear 82 and formed within the bracket 80. The swivel plate 85 is provided with a peripheral groove 88 with which a clamp or set screw 89 is engageable to clamp the swivel plate together with the drilling tool in its different adjusted positions rigidly to the bracket 80.` As illustrated, the bevel ring gear 82 meshes with a bevel gear 90 fixed to a shaft 91 in a plane with the main driving shaft 74. The shaft 91 is journaled in ball bearings 92 carried by the bearingv mergers bracket 484. Als 'xed texzthe' shaft 9`1-isfra spur gear 93, while .ffori'ned withthe opposite endYcf-the shaft-$1 isa sparge-ar 9411 The gears 98 andl94 mesh respectively `with spur ygears`95 and T96, fthe' spur 'gears 95 and 96A fhereinz.con. stituting the .driving lelements Afor the to'ol rotat-v ing and feeding mechanism Thesedriving elements are adapted to eifeotrrotation '.andvfeeding of .a drill .bit or cuttingtooliQ'i through friction 'clutches '98 and f99 Iand a vldiileren'tialscrew mechanism 1100. As' 'this specific-feeding `and rotation rnechariism for the fcut'ting bitf 97 is clearly `described Iin my ic'opendin'g 'applications ser. No. 200,826, filed Jimena; 1927, and ser; No. 255.754, led February `20.1928 inow `matured into Patent No."1;933,`589, patented ENOV.' 7,1933, andina-copending Y application -to one "Richard E. MurphygfSer. No.'-Z74;821",-f1e`dMay 3,` 1928-111OW matured' *into Patent No. fili-$481,376, *patented March l'8, I1193-2, further descriptlon-iof`y the-same is herein believed to\be-"-utineeessar-y otherithan to' statethat the v drill ibit is adapted to V'be r'fed forwardlylat a slow cutting-)speed and retracted aty a relatively high 'speed while they Vsame is `cori'- stantly vrapidly \rot'ated`,r tfast forward "feed, `fo`r positioning or -slow'reve'rse feed 1being"possible by Areversing'frotato'n:of the'shaft 74.- From Ethe foregoingidescriptionf it 'isevident that ythe drilling tools 2 and 3 Vmay be swiveled'ionthecuter ends of the supportingarms'i and rrigidly locked in any of their adjusted positions.' Y

The mechanism yfor-elicoting lrotation lci Ythe boom -ortubular supporting arm '75 within its bearings-"T6 -carried by the frame -el'ements-`55,

'77, '78 herein'comprises a worm gear Y10-1 Akeyed at 101 tothesupportingarm '75 intermediate its supportingbearings. As illustrated meshing with the worm gear -101-isa"worrci 102 herein formed integral rwith' a transverse 'horizontal shaft 103.v This shaft carries at one end a suitable` operating handle 3104. This rotationvmecha'nism for the supporting boom is clearly described Vin `my -co' pendingapp'lications mentioned labove. `--Itris'accordingly evident that the supporting arm -or boom,v upon rotation of lthe Wormlgearing 101,' 102, vmay :be rotated about its longitudinal -axis relativeto lthe swingable housing 50 and-as a result the drilling tool 2 `may fbe swung'ibodily 'about'the airis of 'the supporting' arm. l- JAs this worm gearingli's oftheself-'locking'type thelooornz is Irigidly'lockedagainst 'rotation after such adjustriienlt.A n Y Y 1 v.The improved power operatedrriechanism -"for effecting swingingmovement of the supporting means "4 together withlthe ldrilling'tool supportedthereby ,upwardly vanddownwardly bypower herein comprises a yspur g`earl`05` (see Fig. 55") meshing with rthe Tspur pinion Y'73"lf1xed to the shafts'l, 74 ash'eretofore described. Thisfspur be shifted-axially -tomove'the clutch teeth into interlocking engagement i by means' of ra pivoted shippermember '11?1 -secured-tofla'n operating -rod 112. This operating rod y'is rotatably "mounted within' theffra'mel portion 55- andf has'liriedthereto at v`one-"end a suitable operating llever 5113. YSlidably mounted within parallel guideways flil4 engagingthe threads ofEl the 4screwthrea'lded shait block 115 are jparallel linkmember's y118 lin turn pivotally connected at 119 to the upper part of the swivel r housing 41. From the foregoing. descriptionit will bev evident fthat whenlone or theV other o'f the clutches 59, 60ct 62, 6.3`1is `applied and when `l the clutch teeth '109, 110 are connected, the screw threadedfshaft 108.1nay be rotated onedirectionfor Pthe other, thereby vmoving the :trunnicn blockA 115 within itsI g-uideways and swinging the supporting .arm or boom, together with the drilling tooly supported thereby, `into diierent elevations', the rocking frame v5.0 moving withinits bearings relative tothe swivel frame 4l atfthat time. It will th-usf'be seen tthat either `of thedrilling. tools 2 and i3 may Vbeyswung `upwarjdly'or, downwardly by power as desired. c

- Locking devices, 'as shown `in Fig. 8,- are ,eme ployedor maintaining .the turntables 41 on which the `drilling tools are mounted` `in their `different angular :positions relative to the frame 1K0.l These devices -ilfiereineach comprisesma set screwy 120 threadedly connected :to an yupstanding bracket 121 formed on `,the frame l0` and .this set screw abuts jat its innerge'nd a sliding block 122imounted Within a recess t123 in thebracket l21and held Lin position ;by-a detachable pla-te'f124. As shown the sliding block 122 has an arcuate serrated vinner surface 11'25zeng`ageable withqthe Smooth `outer periphery .of a circular Aportion l-26`herein `formed integral withthe swivel frame 410i the turn-r table. It -will therefore be evident that l.upon suitable :adjustment of thefset screw 120 t-heysliding block 122 may -be moved'inwardlycausingthe serrations thereon to grip-the peripheryofthe frame portion 126 thereby-locking the turntableagainst rotation: n v

iElectrical energy -is'vsuplplied to the motor .11 througha conductor-cable 12.7 wound upona cable reel 128 mountedvupon thetruckibody. Suitable guide devices;` 129; are -provided ior .guiding the conductor cablelzil.v Extending Ifrom suitable terminalelementsor plugs ,-130 at'the` sides of the cable reel are conductorcables 41.8.1 leading rin a usual gmanner tothe rmotor elements.- @Secured tothe cablejreel .iszagpulley 132'whichiisY connected by aneendless beltconnection A133 to a.driving.pul. ley :134 secured to a transverse shaft .i135 fjournaled onl the truck fbody 5. This yshaft 11-35 has fxedthereto atits outer end alchain-sprocket 136 connected by a chainand sprocket connection 137 to the reartruck Vaxle 9. lIt will thus be evident that as the apparatus moves along the `trackway the cable reelris driven from-'the rear axle-through chainconnection l-3'7,fdri\ring fpulley134, and belt connection 13-3, the cable-reel automatically Kun- Winding theconductorncable -12'7as the apparatus movesforwardly along the trackway and Winde ingup this lconductor cableautomaticallyas the apparatus moves rearwardly. :Suitable electrical controlling apparatus is providedonthe truckvfor controllingthe supply'of electricalenergy to the motorl-l, :this controlling apparatus :being generally designated at 4138. A `suitable. brakingdeviceis provided for -holding the truck wheels against Arotation and herein comprises -a, brake drum 139 securedto the :reartruck axle9 andy with which a contractible brake fband 140 cooperates. The brakeband 5.140'is provided with suitable operating means including la flever .i141 pivotal1y mountedon the truck lzfrarne 5. "A toothed l segment' 1142 and latch i 1:43 arev employed for maintaining `:the Elever 141 fins its different 1 adjusted positions. "This i brakelis used to :ihold the truckwheels stationary 'duringfthe'rdrilling operation fand to prevent 2 too rapidmovement-.of :the

apparatus while moving along an inclined trackway. l

In the operation of the improved drilling apparatus the same is propelled under its own power along the mine trackway by the motor 11 through the driving connections between the motor and the truck wheels as described above, the desired direction of movement of the apparatus along the trackway being controlled by suitableapplication of the reverse controlling clutches 25, 26 and 29, 30. As the drilling apparatus moves forwardly along the trackway the cable reel 128 pays out the conductor cable 127 and when the apparatus moves rearwardly the conductor cable 127 is automatically wound in by the cable reel. When the drilling apparatus reaches the working face the operator applies the brake 139, 140 holding the truck wheels against rotation thereby maintaining the truck stationary. If it is desired to operate the drilling tools at one side of the trackway to position the same close to the rib the operator releases the clamping devices 120, 122 and swings the turntables 41 thereby moving the supporting means 4 and the drilling tool supported thereby to one side of the truck as indicated by dotted lines in Fig. 1. If it is desired to swing the drilling tools upwardly or downwardly, for instance to bring the drilling tools close to the mine bottom or roof as indicated by dotted lines in Fig. 2, the operator connects the clutch 109, 110 and upon suitable application of the friction clutches 59, 60 and 62, 63 the drilling tools may be swung upwardly or downwardly under motor control as desired. If it is desired to swing the drilling tool about the axis of the supporting arm or boom 75 the operator rotates the worm gearing 101, 102 thereby rotating the supporting boom about its longitudinal axis. The worm gearing 101, 102 is self-locking and the boom is thereafter locked against rotation. When desired the angle of the drilling tool relative to the supporting boom may be changed simply by releasing the clamping screw 89 and bodily swinging the drilling tool relative to the swivel bracket 80. When the drilling tools are suitably positioned adjacent the working face the clutches 98, 99 may be so controlled as to effect slow feeding movement of the drill bits 97 and after the holes are completed the drill bits may be retracted from the face at a high speed in the manner clearly described in the copending applications mentioned above. It will further be noted that the drilling tools may be swung independently to one side or the other of the truck and upwardly or downwardly as desired so that a plurality of holes may be simultaneously drilled in any position, it being possible to swing the drilling tools close to and into parallel relation with the mine roof and bottom or to swing the same vlaterally adjacent either rib.

As a result of this invention an improved selfpropelled multiple tool drilling apparatus is provided wherein the drilling tools are swingable into a plurality of positions relative to the working face, and by employing the improved supporting and adjusting means for the tools the latter may be moved into such positions with facility and expeditiously. It will further be noted that by employing the improved adjustable mountings for the drilling tools the latter may be adjusted rindependently to either side of the truck or upwardly or downwardly as desired, the improved supporting means being so constructed as to permit the drilling tools to be positioned close to and parallel with the mine roof and bottom or adjacent either' rib. Itwill still further' be noted that but a single motor is utilized for propelling the apparatus along the trackway, for swinging the drilling tools upwardly and downwardly, and for driving'the tool rotating and feeding mechanism, the driving connections between the motor and the various elements being of a simple and reliable design adapted to withstand the severe service conditions encountered underground in mines. It will also be noted that the apparatus is wholly self-contained and operates at all times from the mine trackway. It will also be noted that the drill supporting and adjusting and driving mechanisms and the improved truck mounting are equally applicable to single tool drills and it is to be understood that my invention is not limited in its scope to multiple drill mechanisms other than as expressly set forth in certain of the appended claims. These and other uses and advantages of this invention will be clearly apparent to those skilled in the art.

While in this application there is specifically described one form which the invention mayassume in practice, it will be understood that this form of the same isishown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a drilling apparatus, a portable support, a motor thereon, horizontal turntables mounted on said support for rotation about vparallel vertical axes, a forwardly extending adjustable supporting structure mounted upon and supported by each turntable, a drilling tool mounted on the outer extremity of each supporting structure, and driving connections between said motor and said drilling tools. I

2. In a drilling apparatus, a portable support, a motor thereon, horizontal turntables mounted on said support for rotation about parallel vertical axes, a forwardly extending adjustable supporting structure mounted upon and supported by each turntable, a drilling tool mounted on the outer extremity of each supporting structure, driving connections between said motor and said drilling tools, and mechanism driven by said motor` for propelling said support.

3. In a drilling apparatus, a portable support, a motor thereon, horizontal turntables mounted on said support, a forwardly extending boom pivotally mounted at its rear end on each turntable, a drilling tool .carried at the outer end of each boom, and driving connections between said motor and said drilling tools.

4. In a drilling apparatus, a portable support, a motor thereon, horizontal turntables mounted on said support, a forwardly extending boom pivotally mounted at its rear end on each turntable, a drilling tool pivotally mounted at the outerend of each boom, and driving connections between said motor and said drilling tools.

5. In a drilling apparatus, a portable support, a motor thereon, a plurality of rotatable supports on said support at the forward end thereof, forwardly extending adjustable supports on said rotatable supports and overhanging and extending a substantial distance in advance of said portable support, a drilling tool carried at the outer end of each adjustable support in advance of said portable support, and drivingconnections between said motor and said drilling tools.

6. In a drilling apparatus, a portable support,

a pair of rotatable supports thereon at. the front boom, a motor, Ir'nechanism,driven'rbysaid Ino-l end thereof, a forwardly extending boom pivotally mounted at its rear end on eachl rotatable support.

and overhanging and extending a substantial distance in advance of said portable support, a drilling tool-carried at the outer end of each boom in advance of said portable support, and a motor on.

saidsupport for driving both of said drilling tools. '7. In 'a drilling apparatus, a portable support,

a pair of rotatable supports thereon, a forwardly extending boom pivotally mounted at its rear end' on each rotatable support, a drilling tool carried at the outer-endl of each boom, a motor on said support for driving both of said drilling tools, and mechanism driven by 'said motor for swinging said booms about their pivots.

8. In a drilling apparatus, a portable support: a pair of'rotatable rsupports thereon, a forwardly extending boom pivotally mounted at its rear. 'end on eachfrotatablesupport for swinging movement about a horizontal axis, said booms also being mounted on said rotatable supportsk for rotation about* theirr longitudinal axes, a drilling Y.

tool carried 'at the vouter end ofeachboom, and a ymotor on said support for driving both of` said drilling; tools.

9. In a drilling apparatus, a portablevsupport, a pair of rotatable' supports thereon-,fa'forwardly extending boom pivotally mounted at its rear `Aenden each rotatable support `for swinging movement about a horizontal axis, said booms also being mounted on said rotatable supports for rotation about their longitudinal `axes,; a 'drilling tool carried at the outer end of each bo'omymecha- "nisrn for rotating saidvboomsabout their longitudinal axes, and a motor "on said gsupport forv driving both of said drilling tools.

.10. In a drilling apparatus, a portable support;

a 'pair of rotatable supports thereon, a forwardly extending boompivotally mounted at its rear end on each rotatable support for swinging movement about a horizontal axis, said booms also beingrnounted on said rotatable supports for rotation'about their "longitudinal axes, adrilling tool carried at the outer end of each boom, mechanisrn4 for rotating said booms about their longizontal axis on each turntable, a drilling toolpivotallymounted on` the outer end of Yeach boom,

mechanism for adjusting said booms about their axes including a motor, and ymecl'iam'ismdrivenV swinging movement in `vertical planes extending bysaid motor for driving said drilling tools.

V12. In adrilling apparatus, a portable support, a motor thereon, apair of turntables on said support rotatable aboutiparallel axes, a forwardly extending tubular boom pivotally mounted on a (horizontal axis on each turntable, a drilling tool "pivotally mounted on the outer end of eachboom,

mechanism for adjusting said boomsabout their axes including a motor, and mechanism driven by said motor for driving saiddrillingtool'sincluding driving connectionsextending through said tubular booms.

13. Inv a drilling apparatus, a portable support', va" forwardly extending boom pivotallyl a drilling tool carried attheouter end: ofsaid tor for driving said drilling tool including driving elements arranged with; their axes alined with saidy boom-swing axes `respectively, and mechanism driven by said motor through said driving elements for swinging said boom about one of its vertical pla-ne of the apparatus, anelongated sup-- porting arm plvotally mounted on each turntable for swinging movement in vertical planes extending longitudin'allyiof saidsupport about a hori-` zontal axis, `motor` drivenimechanism for swing-1 ing said armsrabout their axes, a drilling tool car-` ried at the outer .end of eacharm, said'arms be ing `swingable as aforesaid to `position the drilling tools to drill holes at .different elevations in a direction parallel with the longitudinal axis of the apparatus, andrmotor driven mechanism for driving said drilling tools.-. u

115,. In a` drilling apparatus, a self-propelled ed on the l-forwardrendiofsaid support for rotation about parallel vertical axes* at .opposite sides of and'spacedzequally fromithe central longitudinal verticalV plane of the apparatus,` an elongated supi porting arm pivotally mounted on each turntable [for lswinging `movement about a horizontal axis,

motor driven mechanism for swinging said armsA about their axes, a drilling tool pivotally mounted atthe outer end4 of'each arm to'swing relative thereto about an'axis at right angles to the rlo'n'gi` tudinal axis of said arm, `and motor drivenrnechanismfor driving saiddrilling tools.

16. In a drillingapparatus, a self-propelled support, a pair of horizontal turntablesmount'ed on the forward end of said support` for 'rotation about parallel vertical axes,` an elongated" supporting s arm Vpivotallymounted'on eachl turntable. for swinging' movement-f about a 'horizontal axis, mo-l tor` vdriven mechanism fori-swinging said-'arms about their axes, a drilling tool carried at the outer end of each arm, and motor drivenmechanism for driving said drilling tools including a motor '1 carried on Said support, and'driving 'connections between said motortand each drilling, tool including transmission elements extending through said and spacedl equally 'from the central longitudinal vertical p laneof the apparatus,an elongated boom pivotally mounted 'on each of said turntables for longitudinally of the apparatus about a horizontal axis, mechanism for `effecting swinging movement of said booms about their axes, and a drilling toolr pivotally mounted 'on the outer end of'each boom and adjustable in aforesaid vertical direction relative tosaid support into positions to drill holes at different-elevations-in a direction extending longitudinallyk of thel apparatus.

18. In addrilling apparatus, a portable support, a pair of horizontal turntables thereon rotatable f about parallel 'verticall axes, anl elongated boom pivotally mounted on each of saidturntables vfor swinging movement about afhorizontal axis,`

mechanism for effecting swinging movement of said booms about their axes including a motor, anda'dlillingtool pivotally mounted on the outer support,-.a Apair of horizontal turntables mount-` end of each boom, both saiddrilling tools driven by said motor.

19. In a drilling apparatus, a portable support, a motor carried thereby, a horizontal turntable on said support rotatable about a vertical axis, an elongated boom pivotally mountedon said turntable for swinging movement about a horizontalk axis relative to said motor and turntable, mechanism driven by said motor for effecting swinging. movement of said boom about its pivot and including driving elements arranged with their axes alined with the turntable and boom axes aforesaid, and a drilling tool pivotally mounted on the outer end of said boom.

20. In a drilling apparatus, a portable support, a motor carried thereby, a horizontal turntable on said support rotatable about a vertical axis,'

the position of the drilling tool relative to said' support.

21. In a drilling apparatus, a portable support, a motor thereon, an elongated supporting arm pivotally mounted atits rear end on said support for swinging movement about vertical and horizontal axes, said arm being swingable horizontally and vertically about said axes relative to said support and motor, a drilling tool adjustably mounted on the outer extremity of vsaid arm, mechanism driven by said motor for driving said drilling tool and including driving elements arranged with their axes alined with the arm swing axes, and mechanism driven by said motor through said drivingelements for swinging said arm vertically about -said horizontalL axis.

22. In a drilling apparatus, a Wheeled truck, a motor thereon for driving the truck wheels to propel the apparatus along the trackway, an

'elongated supporting arm pivotally mounted at its rear end on said truck for swinging movement about angularly disposed axes, said arm being adjustable vertically and horizontally about said axes, mechanism driven by said motor `for swinging said arm about one of its pivotal axes, a drilling tool adjustably-mounted on the outer extremity of said arm, and driving'connections between said motor and said drilling tool.

23. In a drilling apparatus, a wheeled truck,

a motor thereon for driving the truck wheels tof propel the apparatus along a trackway, an elongated supporting arm pivotally mounted at its rear end on said truck for swinging movement about angularly disposed axes including a Vhorizontal pivotal axis, a drilling tool adjustably mounted on the outer extremity of said arm, mechanism driven by said motor for swinging said arm about its horizontal pivotal axis to swing said arm vertically to adjust said drilling =tool into different parallel positions, said arm being swingable horizontally to adjust said drilling tool into different parallel positions at opposite sides of said truck, and driving connections between said motor and said drilling tool.

24. In a drilling apparatus, a portable support,

a motor thereon, an elongated supporting arm pivotally mounted at its rear end on said support for swinging movement about Vertical and horizontal axes, said .arm being swingable horizontally and vertically about said axes, mechanism driven by said motor for swinging said arm vertically about said horizontal axis, a drilling tool adjustably mounted on the outer extremity of said arm, mechanism for rotating said arm about its longitudinal axis to move said drilling tool into different positions about said longitudinal axis, and driving connections between said motor and said drilling tool.

25. In a drilling apparatus, a wheeled truck, a motor thereon for driving the truck wheels to propel the apparatus along the trackway, an elongated supporting arm pivotally mounted at its rear end on said truck for swinging movement about angularly disposed axes, said arm being adjustable vertically and horizontally about said axes, mechanism driven by said motor for swinging said arm about one of its pivotal axes aforesaid, a drilling tool adjustably mounted on the outer extremity of said arm, mechanism for rotating said arm about its longitudinal axis to move said drilling tool into different positions about said longitudinal axis, and driving connections between said motor and said drilling tool.

26. In a drillingfapparatus, a wheeled truck, a motor thereon for driving the truck wheels to propel the apparatus along a trackway, an elongated supporting arm pivotally mounted at its rear end on said truck for swinging movement about angularly disposed axes including a horizontal pivotal axis, a drilling. tool adjustably mounted on the outer extremity of said arm, mechanism for rotating said arm about its longitudinal axis to move said drilling tool into different positions about said longitudinal axis, mechanism driven by said motor for swinging said arm about its horizontal pivotal axis to swing the same vertically to position said drilling tool into different parallel positions, said arm being swingable horizontally to position said drilling tool into different parallel positions at opposite sides of said truck, and driving connections between said motor and said drilling tool.

27. In a drilling apparatus, a portable support, an elongated supporting arm pivotally mounted on said support for swinging movement about a horizontal pivot axis, a drilling tool adjustably mounted on the outer extremity of said arm, a motor, and mechanism driven by said motor for swinging said arm upwardly and downwardly about its pivot to position said drilling tool into different parallel planes and including a driving element arranged with its axis aligned with the arm pivot axis.

28. In a drilling apparatus, a portable support, an elongated supporting structure adjustably mounted on said support and extending a substantial distance in advance of said support, a drilling tool adjustably mounted on the outer l extremity of said supporting structure, said supporting structure being adjustable to position said drilling tool in a plurality of relatively high and relatively low parallel planes and into positions at either side4 of said support, a motor on said support relative to which said supporting structure is adjustable as aforesaid, mechanism driven by saidmotor for drivingthe drilling tool and including a driving element arranged with its axis extending longitudinally of said supporting structure, and mechanism driven by said motor ness-avai 29'. In a drilling` apparatus, ay portable support, an elongated supportingstructure adjustably mounted on saidfsupp'ort andextending a` substantial distance advance ofvsaidz support;

a Vdrilling toolr adjustably: mounted on the outer extremity ofsaid supporting structure, said sup-fy porting structure being adjustable to position said drilling toolin a pluralityof relatively high and relatively lowfparall'el planesand intopositions at either side of' said support, a motor, mechanism Adriven by 'said motor for driving the drilling tool;V vmechanism 'driven'fby said' -rnotor for adjusting `said'supporting structure relative; to said support, and mechanism driven` by saidz gitudinal` axis to position the drilling tool into different positions either below, above, 'or either motor:r for propelling the f apparatus.4 f

30. In ai, drilling apparatus, a-portable sup-f port, a turntable thereon, means :for locking', said f turntable inits diierentpositions of adjustment relative'to saidAv supportnari` elongated supporting structuread-justablymounted. at its rear endI on said turntableior adjustment-into different lating, structure,- 'said'v tool kbeing;-adjustabl'e:witlr said supportingstructure intodierent parallel elevated positions and intoy different parallel latieral positions relativeto saidsupport, and means"- for driving-'the drilling tool# and.l effecting cer-l tainy adjustments yof said" supporting structurer; y

1 supporting structures being'adjustable rto'posirelative toi said support including amotor rela'- tive to which saidl supporting structure is: adjust-f able, and 'driving elements driven by' said inotor and including a driving felernentarranged,"with-` its axis extending longitudinally of said 'supporting structure and through which` saidwadjusting means is driven.v f

31. In a drilling apparatus, aportable sup port, a turntable thereon,"means for locking said' a-pair of independently adjustable elongate'dsup-` portingstructures mounted at their rear ends on" i the forwardtend offsaid'support, said'fsup'porting structures at their rearward ends overlying said supportl and extending forwardly a substantialA turntable in its diierent positionsof adjustment relative to said supportgan elongated support-r ing structure adjustably mounted at itsd rear end ort said7 turntable for adjustment 'into different lateral' positions and 'intoi different elevated posi'- tions relative thereto; a-drilflingtool: adjustably mounted on the outer extremity or said supporting structure, said tool being adjustablewith said supporting structureI into different parallel vele,`

vated" positions and into different parallel lat. eral ,positions relativev to said? support,Y a motor: forA driving the drilling tool andl effecting; certainY adjustments of said supporting r-structure relative to said support, and' mechanism driven by said motor `for propelling thef apparatus.

32, Inf a drilling apparatus;l a-L portable support, a turntable thereon, meansvfor'lockingi said. turntable in its different position's'ot adjustment relative tosaid' support, an elongated supporting structure adjustably mounted at its rear :ende on saidturntable for adjustment into diierent lat-jl on the forward end of saidsupport and* extending eral positions and into different'elevated'jpositions relative thereto, a drilling tool" adjustably vatedY positions ande into different parallel lateral'.

positionsrelative to said. support, mechanismffor turning saidsupporting structure about. its-longitudinal. axis to .adjust the drilling tool into different positions either below, above, or at either side` of said, supporting, structure,` and ,al motor n. for driving. the drilling, tool` andelecting; cerv,

tain: :adjustments voi?. `said 'supporting structure relative to said support. f i f v `33. In a drilling apparatus', a portable support, a turntablethereon, means /for lockin'gsaid turntable in its different positions of adjustment relal tive to said. support, an elongated supporting structure adjustably mountedatlits rear end on said turntable for adjustment into different latsideA of said supporting structure; a'zmotor yfor 'driving the drilling tool and effecting certain ad` justments of said` supporting structure` relative to said support, and mechanism driven by said motor y for propelling the apparatus.

34; yIn a drilling apparatus,` a pcsrtablesupport,l

a pai-r of independently adjustable elongated supportingstructures mounted at their rear ends' on' theforward end of said `support,`said supporting structures at theirk rearward ends overlying said support and extending yforwardly a substantial distancein advance of said support, a drilling tool supported ony the-outerextremityiof each `supporting. structure in advance of said supportgsaid tion said' drilling toolsinto different relatively high parallel positions and into different relatively low parallel positions relative' to said support and in diierent 'lateral positions toenable sai'dtools to drill holes above, below and at either side'v of said support, a-motor on said support; and driv- I ing connections between'saidmotor and said' tools.`

35,111 a drilling apparatus, a portable support,

distance in advance of said support, a drilling toolV supported on the outer extremity of each supporting' structure-in advance of said support, saidvsupporting structures being adjustable to position said drilling tools into different relatively z higlrparallelpositions and-into different relatively low parallel positions relative tosaid support and intoI diirerentlateralv positions to enable'said tools to drillv holes above,'below and*l at either side'of f said support, a motor on said support, driving connections between said motor and said tools, andmechanism` driven by said motor for propelling saidY support.V '1 k f, i

'36u In a drillingI apparatus, a portable support, a pair of independently adjustable `elongated supporting structures mounted at their rear ends a substantial distance in advance yof said support,

turesk being adjustable to positionsaidA drillingtoolsinto different relatively high parallel' posi- 'tions and into different relatively low parallel .positions relative tosaid support and intodiifery ent lateral lpositions torenable saidy tools: to drillV holes above, below `andf-at either side of said support, a motor on saidpsupport, driving c'on-vr nections between saidl motor and said,toolsl and lol 2e ff i so* cal?" mechanism driven by said motor for independently adjusting said supporting structures.

37. In a drilling apparatus, a portable support, an elongated supporting structure mounted at its rear end on the forward end of said support and extending a substantial distance in advance thereof, a drilling tool carried at the outer extremity of said supporting structure, said supporting structure being adjustable to position said tool of said supporting structure.

38. .In a drilling apparatus, a portable support, an elongated supporting structure mounted at its rear end on the forward end of said support and extending a substantial distance in advance therelof, a drilling tool carried at the outer extremityA of said supporting structure, said supporting structure being adjustable to position said tool above, below and laterally at the side of said support to position said tool into different relatively :high and relatively low planes and different lateral planes, a motor on said support'relative to which said supporting structure is adjustable for driving said tool, and mechanism driven by said motoi` for adjusting said supporting structure relative to said support.

39. In a drilling apparatus, a portable support,

a pair of independently adjustable elongated supporting structures mounted at their rear ends on the forward end of said support and extending a rsubstantial distance in advance of said support,

lateral positions to enable said tools to drill holes in advance of said support in a direction parallel tothe longitudinal axis of the apparatus, said tools being adjustable to drill holes above, below and at either side of said support, and motor operated devices including driving elements common to the drive of both tools for driving said drilling tools.

40. In a drilling apparatus, a portable support,

a pair of independently adjustable elongated sup-v porting structures mounted at their rear ends on said support at opposite sides ofthe latter and extending a substantial distance in advance of said support, a drilling tool supported on the outer extremity of each supporting structure, said supporting structures being adjustable in vertical planes extending longitudinally of the apparatus to position said drilling tools into different relatively high parallel positions and into diiTerent relatively low parallel positions relative to said support and into different lateral positions to enable said tools to drill holes in advance of said support in a direction parallel to the longitudinal axis of the apparatus, said tools being adjustable to drill holes above, below and at either side of said-support, and motor operated devices including driving elements common to the drive of both tools fordriving said drilling tools.

41. In a drilling apparatus, a portable support, a pair of independently adjustable elongated supporting structures mounted at their rear ends on said support for swinging movement about parallel axes and extending a substantial distance in advance-of said support, a drilling tool supported on the outer extremity of each supporting structure, said supporting structures'being adjustable in vertical planes extending longitudinally of the apparatus to position said drilling tools into different relatively high parallel positions and into different relatively low parallel positions relative `to said support and into different lateral positions to enable said tools to drill holes in ad-` vance of said support in a direction parallel to the longitudinal axis of the apparatus, said tools being adjustable to drill holes above, below and at either side of said support, and motor operated devices including driving elements common to the drive of both tools for driving said drilling tools.

42. Inra drilling'apparatus, a portable support, a pair of independently adjustable elongated supporting structures mounted at their rear ends on the forward end of said support and extending a substantial distancel in advance of said support, said supporting structures being adjustable vertically and laterally relative to said support, a drilling tool supported on the outer extremity of each supporting structure, said supporting structures being adjustable in longitudinal planes relative to said support to position said drilling tools into different relatively high parallel positions and into different relatively low parallel positions relative to said support and into different lateral positions to enable said tools to drill a series of parallel longitudinally extending holes in the working face in advance of the apparatus, said tools being adjustable to drill holes above, below and at either side of said support, and motor operated devices including driving elements common to the drive of both tools for driving said drilling tools.

43.' In a drilling apparatus, a portable support, a pair of independently adjustable elongated supporting structures mounted at their rear ends to swing about rectangularly related axes on the forward end of said support and extending a substantial distance in advance of said support, said supporting structures being adjustable about v their axes both vertically and laterally relative to said support, a drilling tool supported on the outer extremity of each supporting structure and adjustable relative to the latter in planes parallel with the longitudinal axis of said supporting structure, said supporting structures being adjustable to position said drilling tools into different relatively high parallel positions and into diierent relatively low parallel positions relative to said support and into dilierent lateral positions to enable said tools to drill holes above, below and at either side of said support, and motor operated devices including driving elements common to the drive of both' tools for driving said drilling tools.

44. In a drilling apparatus, a portable support, a pair of independently adjustable elongated supporting structures mounted at their rear ends on the top of said support, said supporting structures overlying said support and extending forwardly a substantial distance in advance of said support, a drilling tool supported on the outer extremity of each supporting structure in advance of said support, said supporting structures being adjustable to position said drilling tools into different lateral' positions relative to said support, `a motor carried by said support and relative to which said supporting structures are adjustable, and driving connections between said motor and said drilling tools. f

45. In a drilling apparatus, a portable Support, a pair of independently adjustable elongated supporting structures mounted at their rear ends on the top of said support, said supporting structures 'overlying said support and extending forwardly a substantial distance in advance of said support, a drilling tool mounted on the outer extremity of each supporting structure in advance of said support, said supporting structures being adjustable to position said drilling tools into diierent elevated positions and into different lateral positions to enable said tools to drill holes above, below and at either side of said support, a motor carried` by said support andl relative to which said supporting structures are adjustable, and driving connections between said motor and said drilling tools. l v

46. In a drilling apparatus, a portable support, a pair of independently adjustable elongated supporting structures mounted at their rear ends on the top of said support, said supporting structures overlying said support and extending forwardly a substantialdistance in advance of said support, a drilling tool supported on the outer extremity of each supporting structure in advance of said support, said supporting structures being adjustable to position said drilling tools into dilerent lateral positions relative to said support, a motor carried by said support and relative to` which Said supporting structures are adjustable, driving connections between said motor and said drilling tools, and devices driven by said motor for propelling the apparatus.

47. In a drilling apparatus, a portable support, a pair of independently adjustable elongated supporting structures mounted at their rear ends on said support and extending a substantial distance in advance of saidsupport, a drilling tool mounted on the outer extremity of each supporting structure, said supporting structures being adjustable to position said drilling tools into different elevated positions and into different lateral positions to enable said tools to drill holes above, be- 10W and at either side of said support, a motol` carried by said support and relative to which said supporting structures are adjustable, driving connections between said motor and said drilling tools, and devices driven by said motor for adjusting said supporting structures relative to said support.

48. In a drilling apparatus, a portable support, a pair of independently adjustable elongated suD- porting structures mounted at their rear ends on the forward end of said support and extending a substantial distance in advance of said support, said supporting structures being adjustable in a vertical direction relative to said support, a drilling tool supported on the outer extremity of each supporting structure and adjustable angularly in a vertical direction relative thereto about an axis extending transversely of its supporting structure to drill holes in relatively inclined planes above and below said supporting structure, said supporting structures being adjustable to position said drilling tools into different relatively high parallel positions and into different relatively low parallel positions relative to said support and into different lateral positions to enable said tools to drill holes in planes above, below and at either side of said support, and motor operated devices including driving elements coinmonl to the drive of both tools for driving said drilling tools.

inclined planes above and below said supporting structure, said supporting structures being adjustable to position said drilling tools into difierent relatively high parallel positions "and into different relatively low parallel positions relative s to said support and intodiiferent lateral positions to enable said tools to drill holes in planes above, below and at either side of said support, and motor operated devices including driving elements common to the drive of both tools for driving said drilling tools.

50. In a drilling apparatus, a portable support, a pair of independently adjustable elongated supporting structures mounted at their rear endson said support for swinging movement about parallel axes and extending a substantial distance in advance cf said support, a drilling tool supported on the outer extremity of each supporting structure and adjustable angularly in a vertical direction relative thereto `in planes parallel with the longitudinal axis of its supporting structure to drill holes in relatively inclined planes above and below said supporting structure, said supporting structures being adjustable to position said drilling tools into different relatively high parallel positions and into dierent relatively low parallel positions relative to said support and into difierent lateral positions to enable said tools to drill holes in planes above, below and at either side of rsaid support, and motor operated devices including driving elements common to the drive of both tools for driving said drilling tools.

5l. In a drilling apparatus, a portable support, a pair of independently adjustable elongated supporting structures mounted at their rear ends on the forward end of said support and extending a substantial distance in advance of said support, said supporting structures being adjustable vertically and laterally relative to said support, a drilling tool supported on the outer extremity of each supporting structure and adjustable angularly in a vertical direction relative thereto in planes parallel with the longitudinal axis of its supporting structure to drill holes in relatively inclined planes abover and below said supporting structure, said supporting structures being adjustable to position said drilling tools into dierent relatively high parallel positions and into different relatively lovv parallel positions relative to said support and into dii'erent lateral positions to enable said tools to drill holes in planes above,

' below and at either side of said support, and motor operated devices including driving elements commonr to the drive of both tools for driving said drilling tools..

52. In a drilling apparatus, a portable support,

a pair of independently adjustable elongated sup'- K distance in advance of said support, said supporting structures being adjustable about their axes both vertically and laterally relative to said support, a drilling tool supported on the outer extremity of each supporting structure and adjustable angularly in a vertical direction relative thereto in planes parallel with the longitudinal axis of said supporting structure to drill holes in relatively inclined planes above and below said supporting structure, said supporting structures being adjustable to position said drilling tools into different relatively high parallel positions and into diierent relatively lov-J parallel positions relative to said support and into different lateral positions to enable said tools to drill holes in planes above, below and at either side of said support, and motor operated devices including driving elements common to the drive of both tools for driving said drilling tools.

53. In a drilling apparatus, a portable support, a pair of independently adjustable elongated supporting structures mounted at their rear ends on said support and adjustable in horizontal and vertical directions relative to said support, a drilling tool swivelly mounted on the outer extremity of each supporting structure, said supporting structures being adjustable as aforesaid relative to said support and said tools relative to said supporting structures to position the drilling tools to drill a series of parallel holes extending in a direction longitudinally of the apparatus and at any desired position in a working face in advance of the apparatus, and motor operated means including driving elements common to the drive of both tools for driving said tools and for eiiecting one of the adjustments of said supporting structures relative to said support.

54. In a drilling apparatus, a portable support, a pair of independently adjustable elongated supporting structures mounted at their rear ends on said supports and adjustable in horizontal and vertical directions relative to said support, a drilling tool swivelly mounted on the outer extremity of each supporting structure about axes extending transversely of the longitudinal axes of said supporting structures, said supporting structures being adjustable as aforesaid relative to said support and said tools relative to said supporting structures to position the drilling tools to drill a series of parallel holes extending in a direction longitudinally of the apparatus and at any desired position in a working face in advance of the apparatus, and motor operated means including driving elements common to the drive of both tools for driving said tools and for effecting a certain adjustment of said supporting structures relative to said support.

MORRIS P. HOLMES. 

